Reigning Wimbledon champion Garbine Muguruza trounced top-ranked defending champion Karolina Pliskova 6-3, 6-2 Saturday to reach the final of the WTA and ATP Cincinnati Masters.
The sixth-ranked Spaniard reached her first US event final by flipping the script in a rematch of their 2016 Cincinnati semi-final.
"I'm just happy to be in the final," said Muguruza. "I was hoping to get it and my concentration was really good. Very happy with this win."
Muguruza will play Halep or Stephens
Muguruza advanced to Sunday's final against the winner of a later match between Romania's second-ranked Simona Halep and 151st-ranked US wildcard Sloane Stephens.
Halep would overtake Pliskova and claim the world number one ranking for the first time in her career by winning the Cincinnati crown.
Pliskova had won six matches in a row over Muguruza since losing their first meeting in the first round of the 2013 French Open.
"I lost to her so many times, I figured out something was going wrong," Muguruza said. "I worked hard on beating these kinds of opponents. I returned well. My shots were there. It was a gorgeous day."
Muguruza won at Wimbledon
Last month, Muguruza won her second Grand Slam after the 2016 French Open and her fourth career title on the All-England grass.
Pliskova, last year's US Open runner-up, sought her fourth title of the year after Brisbane, Doha and Eastbourne. Serena Williams from 2014 and 2015 remains the only back-to-back Cincinnati women's winner.
Muguruza, her left thigh bandaged, blasted a backhand winner on her fourth break point to take the opening game of the match and broke again on another backhand winner to take the first set after 36 minutes.
Pliskova was denied on three break points in the second set's opening game, the only ones she faced in the match, and Muguruza broke to 4-2 with another backhand winner.
In the final game, Pliskova saved four match before sending a forehand wide to surrender the break and the match after 79 minutes.
Muguruza hunting top spot
While she can't do it this week, Muguruza would be in the hunt for the top ranking at the US Open, which starts on August 28.
"I'm definitely not thinking at all about number one," Muguruza said. "It's not going to help me. It's going to hold me back. I'm thinking about how I'm playing and if I keep doing that maybe that's going to get me to number one."
Halep, who won her 15th career title at Madrid in May, has not dropped a set this week.
Stephens is playing in only her fourth event since returning from a foot injury that required surgery in January. Her run ensures she will return to the top-100 in Monday's world rankings.
In later men's semi-finals, Australia's Nick Kyrgios will face Spaniard David Ferrer and American John Isner will meet Bulgaria's Grigor Dimitrov.
Ferrer, 35, is the oldest Cincinnati semi-finalist since 1970 champion Ken Rosewall. He won his lone Masters crown in 2012 at Paris.
Neither Kyrgios nor Dimitrov have ever reached an ATP Masters final while Isner is 0-3 in such matches.